Mobile radio-telephone terminals are general usage terminals provided with a reader for a SIM (subscriber identification module) chip card identifying the user and verifying payment of a subscription to the radio network concerned. The chip card thus constitutes an electronic key of the terminal.
Such usage of the terminal, however, has disadvantages.
In the first place, any subscriber having misappropriated a terminal could in some cases use it with his own SIM card. Provision is made to input, via a keypad on the terminal, an identification code word for each subscriber, called a PIN (personal identification number) but it can control only the usage of the associated SIM card and thus be ineffective against fraudulent usage of a terminal.
Another case which could arise is that of loaning the terminal for a duration, a calendar period or period of effective usage, limited, for example, to the clients of a hotel. It must be possible to prevent usage of the SIM card and of the terminal after this period.
The present invention aims to resolve these problems.
To this end the invention relates to a mobile radio-telephone terminal comprising radio means arranged to be activated by a chip card, the chip card comprising memory means containing a subscriber identification word and connected to an input of a comparator, the terminal comprising means for receiving the card, which are connected to the radio means, means for inputting a particular identification word, associated with the card, and arranged to be connected to the other input of the comparator, characterised in that it comprises means for matching it with the card, which are arranged to control the activation of the radio means from the subscriber identification word.
Thus the two constituents of the terminal-card assembly with a word to be input cannot be used separately from each other. A misappropriated or expired card cannot therefore be used on another terminal and, inversely, a stolen terminal cannot be controlled by just any card.
In the prior art the chip card and the input means functionally constituted an autonomous command unit, controlling, without any other means of control, the radio means.
In accordance with the invention the afore-mentioned unit no longer has this autonomy since the terminal has matching means which control the action of the chip card upon the radio means. The terminal is thus personalised and the card is linked thereto.
In a preferred embodiment the matching means comprise, between the input means and the reception means of the card, means for transcoding the input word.
In this embodiment the autonomy of the command unit is controlled by the fact that the identification word indicated to the user is actually fictitious and only becomes real, ie. identical to that in the memory, by virtue of the transcoding means of the terminal. The card can therefore activate the radio means of a terminal only if this terminal is the one which carries out the expected transcoding.
To summarise, the card is slave to the terminal which is itself slave to the card.
In particular the identification word carried by the chip card remains secret to any user, authorised or not, since the PIN word which the user inputs is distinct from that in the memory.
In another preferred embodiment the matching means comprise memory means containing data matched with the data contained in the memory means of the card, controlling comparator means arranged to read the memory means of the card and to authorise activation of the radio means only after the said match has been verified.
Thus the matching is controlled very simply.
The invention will be better understood with the aid of the following description of an example including the two afore-mentioned preferred embodiments of the invention, with reference to the single figure of the attached drawing.